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1 /*
2  * TLSv1 Record Protocol
3  * Copyright (c) 2006-2011, Jouni Malinen <j@w1.fi>
4  *
5  * This software may be distributed under the terms of the BSD license.
6  * See README for more details.
7  */
8 
9 #include "includes.h"
10 
11 #include "common.h"
12 #include "crypto/md5.h"
13 #include "crypto/sha1.h"
14 #include "crypto/sha256.h"
15 #include "tlsv1_common.h"
16 #include "tlsv1_record.h"
17 
18 
19 /**
20  * tlsv1_record_set_cipher_suite - TLS record layer: Set cipher suite
21  * @rl: Pointer to TLS record layer data
22  * @cipher_suite: New cipher suite
23  * Returns: 0 on success, -1 on failure
24  *
25  * This function is used to prepare TLS record layer for cipher suite change.
26  * tlsv1_record_change_write_cipher() and
27  * tlsv1_record_change_read_cipher() functions can then be used to change the
28  * currently used ciphers.
29  */
tlsv1_record_set_cipher_suite(struct tlsv1_record_layer * rl,u16 cipher_suite)30 int tlsv1_record_set_cipher_suite(struct tlsv1_record_layer *rl,
31 				  u16 cipher_suite)
32 {
33 	const struct tls_cipher_suite *suite;
34 	const struct tls_cipher_data *data;
35 
36 	wpa_printf(MSG_DEBUG, "TLSv1: Selected cipher suite: 0x%04x",
37 		   cipher_suite);
38 	rl->cipher_suite = cipher_suite;
39 
40 	suite = tls_get_cipher_suite(cipher_suite);
41 	if (suite == NULL)
42 		return -1;
43 
44 	if (suite->hash == TLS_HASH_MD5) {
45 		rl->hash_alg = CRYPTO_HASH_ALG_HMAC_MD5;
46 		rl->hash_size = MD5_MAC_LEN;
47 	} else if (suite->hash == TLS_HASH_SHA) {
48 		rl->hash_alg = CRYPTO_HASH_ALG_HMAC_SHA1;
49 		rl->hash_size = SHA1_MAC_LEN;
50 	} else if (suite->hash == TLS_HASH_SHA256) {
51 		rl->hash_alg = CRYPTO_HASH_ALG_HMAC_SHA256;
52 		rl->hash_size = SHA256_MAC_LEN;
53 	}
54 
55 	data = tls_get_cipher_data(suite->cipher);
56 	if (data == NULL)
57 		return -1;
58 
59 	rl->key_material_len = data->key_material;
60 	rl->iv_size = data->block_size;
61 	rl->cipher_alg = data->alg;
62 
63 	return 0;
64 }
65 
66 
67 /**
68  * tlsv1_record_change_write_cipher - TLS record layer: Change write cipher
69  * @rl: Pointer to TLS record layer data
70  * Returns: 0 on success (cipher changed), -1 on failure
71  *
72  * This function changes TLS record layer to use the new cipher suite
73  * configured with tlsv1_record_set_cipher_suite() for writing.
74  */
tlsv1_record_change_write_cipher(struct tlsv1_record_layer * rl)75 int tlsv1_record_change_write_cipher(struct tlsv1_record_layer *rl)
76 {
77 	wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - New write cipher suite "
78 		   "0x%04x", rl->cipher_suite);
79 	rl->write_cipher_suite = rl->cipher_suite;
80 	os_memset(rl->write_seq_num, 0, TLS_SEQ_NUM_LEN);
81 
82 	if (rl->write_cbc) {
83 		crypto_cipher_deinit(rl->write_cbc);
84 		rl->write_cbc = NULL;
85 	}
86 	if (rl->cipher_alg != CRYPTO_CIPHER_NULL) {
87 		rl->write_cbc = crypto_cipher_init(rl->cipher_alg,
88 						   rl->write_iv, rl->write_key,
89 						   rl->key_material_len);
90 		if (rl->write_cbc == NULL) {
91 			wpa_printf(MSG_DEBUG, "TLSv1: Failed to initialize "
92 				   "cipher");
93 			return -1;
94 		}
95 	}
96 
97 	return 0;
98 }
99 
100 
101 /**
102  * tlsv1_record_change_read_cipher - TLS record layer: Change read cipher
103  * @rl: Pointer to TLS record layer data
104  * Returns: 0 on success (cipher changed), -1 on failure
105  *
106  * This function changes TLS record layer to use the new cipher suite
107  * configured with tlsv1_record_set_cipher_suite() for reading.
108  */
tlsv1_record_change_read_cipher(struct tlsv1_record_layer * rl)109 int tlsv1_record_change_read_cipher(struct tlsv1_record_layer *rl)
110 {
111 	wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - New read cipher suite "
112 		   "0x%04x", rl->cipher_suite);
113 	rl->read_cipher_suite = rl->cipher_suite;
114 	os_memset(rl->read_seq_num, 0, TLS_SEQ_NUM_LEN);
115 
116 	if (rl->read_cbc) {
117 		crypto_cipher_deinit(rl->read_cbc);
118 		rl->read_cbc = NULL;
119 	}
120 	if (rl->cipher_alg != CRYPTO_CIPHER_NULL) {
121 		rl->read_cbc = crypto_cipher_init(rl->cipher_alg,
122 						  rl->read_iv, rl->read_key,
123 						  rl->key_material_len);
124 		if (rl->read_cbc == NULL) {
125 			wpa_printf(MSG_DEBUG, "TLSv1: Failed to initialize "
126 				   "cipher");
127 			return -1;
128 		}
129 	}
130 
131 	return 0;
132 }
133 
134 
135 /**
136  * tlsv1_record_send - TLS record layer: Send a message
137  * @rl: Pointer to TLS record layer data
138  * @content_type: Content type (TLS_CONTENT_TYPE_*)
139  * @buf: Buffer for the generated TLS message (needs to have extra space for
140  * header, IV (TLS v1.1), and HMAC)
141  * @buf_size: Maximum buf size
142  * @payload: Payload to be sent
143  * @payload_len: Length of the payload
144  * @out_len: Buffer for returning the used buf length
145  * Returns: 0 on success, -1 on failure
146  *
147  * This function fills in the TLS record layer header, adds HMAC, and encrypts
148  * the data using the current write cipher.
149  */
tlsv1_record_send(struct tlsv1_record_layer * rl,u8 content_type,u8 * buf,size_t buf_size,const u8 * payload,size_t payload_len,size_t * out_len)150 int tlsv1_record_send(struct tlsv1_record_layer *rl, u8 content_type, u8 *buf,
151 		      size_t buf_size, const u8 *payload, size_t payload_len,
152 		      size_t *out_len)
153 {
154 	u8 *pos, *ct_start, *length, *cpayload;
155 	struct crypto_hash *hmac;
156 	size_t clen;
157 	int explicit_iv;
158 
159 	pos = buf;
160 	if (pos + TLS_RECORD_HEADER_LEN > buf + buf_size)
161 		return -1;
162 
163 	/* ContentType type */
164 	ct_start = pos;
165 	*pos++ = content_type;
166 	/* ProtocolVersion version */
167 	WPA_PUT_BE16(pos, rl->tls_version);
168 	pos += 2;
169 	/* uint16 length */
170 	length = pos;
171 	WPA_PUT_BE16(length, payload_len);
172 	pos += 2;
173 
174 	cpayload = pos;
175 	explicit_iv = rl->write_cipher_suite != TLS_NULL_WITH_NULL_NULL &&
176 		rl->iv_size && rl->tls_version >= TLS_VERSION_1_1;
177 	if (explicit_iv) {
178 		/* opaque IV[Cipherspec.block_length] */
179 		if (pos + rl->iv_size > buf + buf_size)
180 			return -1;
181 
182 		/*
183 		 * Use random number R per the RFC 4346, 6.2.3.2 CBC Block
184 		 * Cipher option 2a.
185 		 */
186 
187 		if (os_get_random(pos, rl->iv_size))
188 			return -1;
189 		pos += rl->iv_size;
190 	}
191 
192 	/*
193 	 * opaque fragment[TLSPlaintext.length]
194 	 * (opaque content[TLSCompressed.length] in GenericBlockCipher)
195 	 */
196 	if (pos + payload_len > buf + buf_size)
197 		return -1;
198 	os_memmove(pos, payload, payload_len);
199 	pos += payload_len;
200 
201 	if (rl->write_cipher_suite != TLS_NULL_WITH_NULL_NULL) {
202 		/*
203 		 * MAC calculated over seq_num + TLSCompressed.type +
204 		 * TLSCompressed.version + TLSCompressed.length +
205 		 * TLSCompressed.fragment
206 		 */
207 		hmac = crypto_hash_init(rl->hash_alg, rl->write_mac_secret,
208 					rl->hash_size);
209 		if (hmac == NULL) {
210 			wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - Failed "
211 				   "to initialize HMAC");
212 			return -1;
213 		}
214 		crypto_hash_update(hmac, rl->write_seq_num, TLS_SEQ_NUM_LEN);
215 		/* type + version + length + fragment */
216 		crypto_hash_update(hmac, ct_start, TLS_RECORD_HEADER_LEN);
217 		crypto_hash_update(hmac, payload, payload_len);
218 		clen = buf + buf_size - pos;
219 		if (clen < rl->hash_size) {
220 			wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - Not "
221 				   "enough room for MAC");
222 			crypto_hash_finish(hmac, NULL, NULL);
223 			return -1;
224 		}
225 
226 		if (crypto_hash_finish(hmac, pos, &clen) < 0) {
227 			wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - Failed "
228 				   "to calculate HMAC");
229 			return -1;
230 		}
231 		wpa_hexdump(MSG_MSGDUMP, "TLSv1: Record Layer - Write HMAC",
232 			    pos, clen);
233 		pos += clen;
234 		if (rl->iv_size) {
235 			size_t len = pos - cpayload;
236 			size_t pad;
237 			pad = (len + 1) % rl->iv_size;
238 			if (pad)
239 				pad = rl->iv_size - pad;
240 			if (pos + pad + 1 > buf + buf_size) {
241 				wpa_printf(MSG_DEBUG, "TLSv1: No room for "
242 					   "block cipher padding");
243 				return -1;
244 			}
245 			os_memset(pos, pad, pad + 1);
246 			pos += pad + 1;
247 		}
248 
249 		if (crypto_cipher_encrypt(rl->write_cbc, cpayload,
250 					  cpayload, pos - cpayload) < 0)
251 			return -1;
252 	}
253 
254 	WPA_PUT_BE16(length, pos - length - 2);
255 	inc_byte_array(rl->write_seq_num, TLS_SEQ_NUM_LEN);
256 
257 	*out_len = pos - buf;
258 
259 	return 0;
260 }
261 
262 
263 /**
264  * tlsv1_record_receive - TLS record layer: Process a received message
265  * @rl: Pointer to TLS record layer data
266  * @in_data: Received data
267  * @in_len: Length of the received data
268  * @out_data: Buffer for output data (must be at least as long as in_data)
269  * @out_len: Set to maximum out_data length by caller; used to return the
270  * length of the used data
271  * @alert: Buffer for returning an alert value on failure
272  * Returns: Number of bytes used from in_data on success, 0 if record was not
273  *	complete (more data needed), or -1 on failure
274  *
275  * This function decrypts the received message, verifies HMAC and TLS record
276  * layer header.
277  */
tlsv1_record_receive(struct tlsv1_record_layer * rl,const u8 * in_data,size_t in_len,u8 * out_data,size_t * out_len,u8 * alert)278 int tlsv1_record_receive(struct tlsv1_record_layer *rl,
279 			 const u8 *in_data, size_t in_len,
280 			 u8 *out_data, size_t *out_len, u8 *alert)
281 {
282 	size_t i, rlen, hlen;
283 	u8 padlen;
284 	struct crypto_hash *hmac;
285 	u8 len[2], hash[100];
286 	int force_mac_error = 0;
287 	u8 ct;
288 
289 	if (in_len < TLS_RECORD_HEADER_LEN) {
290 		wpa_printf(MSG_DEBUG, "TLSv1: Too short record (in_len=%lu) - "
291 			   "need more data",
292 			   (unsigned long) in_len);
293 		wpa_hexdump(MSG_MSGDUMP, "TLSv1: Record Layer - Received",
294 			    in_data, in_len);
295 		return 0;
296 	}
297 
298 	ct = in_data[0];
299 	rlen = WPA_GET_BE16(in_data + 3);
300 	wpa_printf(MSG_DEBUG, "TLSv1: Received content type %d version %d.%d "
301 		   "length %d", ct, in_data[1], in_data[2], (int) rlen);
302 
303 	/*
304 	 * TLS v1.0 and v1.1 RFCs were not exactly clear on the use of the
305 	 * protocol version in record layer. As such, accept any {03,xx} value
306 	 * to remain compatible with existing implementations.
307 	 */
308 	if (in_data[1] != 0x03) {
309 		wpa_printf(MSG_DEBUG, "TLSv1: Unexpected protocol version "
310 			   "%u.%u", in_data[1], in_data[2]);
311 		*alert = TLS_ALERT_PROTOCOL_VERSION;
312 		return -1;
313 	}
314 
315 	/* TLSCiphertext must not be more than 2^14+2048 bytes */
316 	if (TLS_RECORD_HEADER_LEN + rlen > 18432) {
317 		wpa_printf(MSG_DEBUG, "TLSv1: Record overflow (len=%lu)",
318 			   (unsigned long) (TLS_RECORD_HEADER_LEN + rlen));
319 		*alert = TLS_ALERT_RECORD_OVERFLOW;
320 		return -1;
321 	}
322 
323 	in_data += TLS_RECORD_HEADER_LEN;
324 	in_len -= TLS_RECORD_HEADER_LEN;
325 
326 	if (rlen > in_len) {
327 		wpa_printf(MSG_DEBUG, "TLSv1: Not all record data included "
328 			   "(rlen=%lu > in_len=%lu)",
329 			   (unsigned long) rlen, (unsigned long) in_len);
330 		return 0;
331 	}
332 
333 	wpa_hexdump(MSG_MSGDUMP, "TLSv1: Record Layer - Received",
334 		    in_data, rlen);
335 
336 	if (ct != TLS_CONTENT_TYPE_HANDSHAKE &&
337 	    ct != TLS_CONTENT_TYPE_CHANGE_CIPHER_SPEC &&
338 	    ct != TLS_CONTENT_TYPE_ALERT &&
339 	    ct != TLS_CONTENT_TYPE_APPLICATION_DATA) {
340 		wpa_printf(MSG_DEBUG, "TLSv1: Ignore record with unknown "
341 			   "content type 0x%x", ct);
342 		*alert = TLS_ALERT_UNEXPECTED_MESSAGE;
343 		return -1;
344 	}
345 
346 	in_len = rlen;
347 
348 	if (*out_len < in_len) {
349 		wpa_printf(MSG_DEBUG, "TLSv1: Not enough output buffer for "
350 			   "processing received record");
351 		*alert = TLS_ALERT_INTERNAL_ERROR;
352 		return -1;
353 	}
354 
355 	if (rl->read_cipher_suite != TLS_NULL_WITH_NULL_NULL) {
356 		size_t plen;
357 		if (crypto_cipher_decrypt(rl->read_cbc, in_data,
358 					  out_data, in_len) < 0) {
359 			*alert = TLS_ALERT_DECRYPTION_FAILED;
360 			return -1;
361 		}
362 		plen = in_len;
363 		wpa_hexdump_key(MSG_MSGDUMP, "TLSv1: Record Layer - Decrypted "
364 				"data", out_data, plen);
365 
366 		if (rl->iv_size) {
367 			/*
368 			 * TLS v1.0 defines different alert values for various
369 			 * failures. That may information to aid in attacks, so
370 			 * use the same bad_record_mac alert regardless of the
371 			 * issues.
372 			 *
373 			 * In addition, instead of returning immediately on
374 			 * error, run through the MAC check to make timing
375 			 * attacks more difficult.
376 			 */
377 
378 			if (rl->tls_version >= TLS_VERSION_1_1) {
379 				/* Remove opaque IV[Cipherspec.block_length] */
380 				if (plen < rl->iv_size) {
381 					wpa_printf(MSG_DEBUG, "TLSv1.1: Not "
382 						   "enough room for IV");
383 					force_mac_error = 1;
384 					goto check_mac;
385 				}
386 				os_memmove(out_data, out_data + rl->iv_size,
387 					   plen - rl->iv_size);
388 				plen -= rl->iv_size;
389 			}
390 
391 			/* Verify and remove padding */
392 			if (plen == 0) {
393 				wpa_printf(MSG_DEBUG, "TLSv1: Too short record"
394 					   " (no pad)");
395 				force_mac_error = 1;
396 				goto check_mac;
397 			}
398 			padlen = out_data[plen - 1];
399 			if (padlen >= plen) {
400 				wpa_printf(MSG_DEBUG, "TLSv1: Incorrect pad "
401 					   "length (%u, plen=%lu) in "
402 					   "received record",
403 					   padlen, (unsigned long) plen);
404 				force_mac_error = 1;
405 				goto check_mac;
406 			}
407 			for (i = plen - padlen - 1; i < plen - 1; i++) {
408 				if (out_data[i] != padlen) {
409 					wpa_hexdump(MSG_DEBUG,
410 						    "TLSv1: Invalid pad in "
411 						    "received record",
412 						    out_data + plen - padlen -
413 						    1, padlen + 1);
414 					force_mac_error = 1;
415 					goto check_mac;
416 				}
417 			}
418 
419 			plen -= padlen + 1;
420 
421 			wpa_hexdump_key(MSG_MSGDUMP, "TLSv1: Record Layer - "
422 					"Decrypted data with IV and padding "
423 					"removed", out_data, plen);
424 		}
425 
426 	check_mac:
427 		if (plen < rl->hash_size) {
428 			wpa_printf(MSG_DEBUG, "TLSv1: Too short record; no "
429 				   "hash value");
430 			*alert = TLS_ALERT_BAD_RECORD_MAC;
431 			return -1;
432 		}
433 
434 		plen -= rl->hash_size;
435 
436 		hmac = crypto_hash_init(rl->hash_alg, rl->read_mac_secret,
437 					rl->hash_size);
438 		if (hmac == NULL) {
439 			wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - Failed "
440 				   "to initialize HMAC");
441 			*alert = TLS_ALERT_INTERNAL_ERROR;
442 			return -1;
443 		}
444 
445 		crypto_hash_update(hmac, rl->read_seq_num, TLS_SEQ_NUM_LEN);
446 		/* type + version + length + fragment */
447 		crypto_hash_update(hmac, in_data - TLS_RECORD_HEADER_LEN, 3);
448 		WPA_PUT_BE16(len, plen);
449 		crypto_hash_update(hmac, len, 2);
450 		crypto_hash_update(hmac, out_data, plen);
451 		hlen = sizeof(hash);
452 		if (crypto_hash_finish(hmac, hash, &hlen) < 0) {
453 			wpa_printf(MSG_DEBUG, "TLSv1: Record Layer - Failed "
454 				   "to calculate HMAC");
455 			*alert = TLS_ALERT_INTERNAL_ERROR;
456 			return -1;
457 		}
458 		if (hlen != rl->hash_size ||
459 		    os_memcmp_const(hash, out_data + plen, hlen) != 0 ||
460 		    force_mac_error) {
461 			wpa_printf(MSG_DEBUG, "TLSv1: Invalid HMAC value in "
462 				   "received message (force_mac_error=%d)",
463 				   force_mac_error);
464 			*alert = TLS_ALERT_BAD_RECORD_MAC;
465 			return -1;
466 		}
467 
468 		*out_len = plen;
469 	} else {
470 		os_memcpy(out_data, in_data, in_len);
471 		*out_len = in_len;
472 	}
473 
474 	/* TLSCompressed must not be more than 2^14+1024 bytes */
475 	if (TLS_RECORD_HEADER_LEN + *out_len > 17408) {
476 		wpa_printf(MSG_DEBUG, "TLSv1: Record overflow (len=%lu)",
477 			   (unsigned long) (TLS_RECORD_HEADER_LEN + *out_len));
478 		*alert = TLS_ALERT_RECORD_OVERFLOW;
479 		return -1;
480 	}
481 
482 	inc_byte_array(rl->read_seq_num, TLS_SEQ_NUM_LEN);
483 
484 	return TLS_RECORD_HEADER_LEN + rlen;
485 }
486